The state of the art describes linear drives for belt buckle tensioners having a piston that is shaped onto a cable connected to the belt buckle and that is accommodated in a cylinder. The cylinder is connected to a gas generator that generates compressed gas that acts on the piston and brings about a tensioning stroke in order to eliminate the belt slack of the seatbelt system. With such a linear drive, care must be taken to ensure that the piston (and thus the belt buckle) cannot be displaced in case of pressure or impact on the belt buckle. For this purpose, the cable is normally deflected between the cylinder and the belt buckle in such a way that a great deal of friction is generated. However, this friction is a drawback during the tensioning.
The invention creates a linear drive, especially for a belt buckle tensioner, that stands out over the state of the art for its greater locking force in a pushing direction of the cable.